Coating material

ABSTRACT

The present invention provides a coating suitable for coating woods, and the coating is obtained by dissolving proanthocyanidine into water or a water-containing alcohol.

TECHNICAL FIELD

The present invention relates to a paint comprising proanthocyanidine.

BACKGROUND ART

Coating of wood is generally clear coating which is finished by directlyexpressing the quality and grain of the wood, and the main part of thiscoating art comprises the coating of furnitures. However, the coating ofwoods unlike that of metal materials has a disadvantage that suchcoating cannot be treated regularly due to the type of woods. That is,the properties of woods are distinguished from each other depending onthe kinds of trees, the grains of the surface will vary depending on thesawings of woods, the stretching properties will vary depending on thedirections of grains, and the tissues of the woods are uneven and thusresult in different absorption of a coating.

On the other hand, the clear coating of woods had been started with oilyvarnish and lac varnish, and then a variety of synthetic coatings andcoating methods have been developed by way of cashew coatings as analternative of glue. Furthermore, the coloring methods with chemicalagents have been practiced, but such coatings in the prior art oftenemploy organic solvents, thus resulting in the inconvenience for theirhandling as well as environmental pollution. In addition, such coatingshave also a problem that the coatings are malodorous not only duringcoating but also after coating, and that such coatings are hardly coateduniformly.

DISCLOSURE OF THE INVENTION

The object of the present invention is to provide a coating suitable forthe coating of woods.

The present inventors have conducted examinations in order to solve theabove described problems, and found that proanthocyanidine can be usedas an oil stain-like coating.

Proanthocyanidine is known to have a variety of physiological activitiessuch as anti-oxidation, anti-mutagenesis, cosmetically skin-whiteningeffect, arteriosclerosis-myocardial infarction preventing effect, vesselprotecting effect, anti-tumor effect, angiotensin transferase inhibitingeffect, anti-bacterial effect and deodorant effect, but no reports havebeen described about the use as a coating material.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described specifically below.

Proanthocyanidines are the condensed type tannins present in variousplant bodies, i.e. the compounds in which flavan-3-ol or flavan-3,4-diolas the constructing units are combined by condensation orpolymerization. These compounds are referred to as proanthocyanidinesbecause of the production of anthocyanidines such as procyanidine,delphinidine and pelargonidine by their treatment with acid.Proanthocyanidines such as procyanidine, prodelphinidine andpropelargonidine, and their steric isomers which are the dimer, trimer,tetramer as well as decamer or higher polymer of the above describedconstituent units can be obtained by the extraction of a variety ofplant bodies such as seeds of grape, cranberry fruit, apple fruit,soybean, or barks of cedar, Japanese cypress or pine tree.

These proanthocyanidines are commercially available, and include forexample "KPA" (manufactured by Kikkoman Corp.) which is made from grapeseeds, "APPLEPHENONE" (The Nikka Whiskey Distilling Co., Ltd.) made fromthe pre-mature fruit of apple, "PICNOGENOL" (Horphag Research Limited;GB), and the like.

These proanthocyanidines may be used as coating materials by dissolvingproanthocyanidine into water or water-containing alcohol in aconcentration of 0.1-10% and coating the solution by the conventionalmethod, e.g. applying with brush or spraying with atomizer.Proanthocyanidine in the solution may be freely set up at aconcentration of 0-100%, and the higher concentration solution may beobtained by warming the proanthocyanidine in water or aqueous alcoholdue to the relationship of the solubility of proanthocyanidine. By wayof example, proanthocyanidine is dissolved at a concentration of 0.1-10%in water or aqueous alcohol at an ordinary temperature, and at aconcentration of 10-50% at 35-70° C.

The higher concentration solution may be coated more heavily, so thatthe proanthocyanidine may be dissolved and coated at an appropriatetemperature depending on purposes. The coating is carried out one toseveral times in order to impregnate proanthocyanidine into the surfaceof a material to be coated. As the proanthocyanidine gradually permeatesfrom the surface of the material to be coated into the inside, firm filmis formed on the surface by its polymerization with ultraviolet rays.

While proanthocyanidine just coated on wood remains colorless andtransparent, it absorbs ultraviolet rays and gradually turns darkened,and thus resulting in a pale brownish coating. The darkening is causedby the polymerization of proanthocyanidine.

Such polymerization mechanism is the same as that in glue, and goodcoating condition can be maintained over a longe period without peelingoff of the coating.

Also, the post-treatment of a coating device can be readily done, sincethe solvent used is water or an alcohol. In addition, the coatingmaterial of the present invention may be also used in combination withthe other aqueous coating materials.

The material to be coated includes woods, paper, fiber (thread), and thelike. The coating material of the present invention can be coatedparticularly on woods for the coating with utilizing the grains, so thatit is useful for the coating of the alcove post, a horizontal piece oftimber, ceiling board, and the like as well as furnitures and indoorfurnishings. It also improves the anti-corrosion and thus can besuitably applied to outer wall, gate, terrace or log house.

Also, when a proanthocyanidine solution is coated, the polymerization ofproanthocyanidine can be further promoted by incorporating oxidase orperoxidase such as laccase, which may act on proanthocyanidine as asubstrate, in the proanthocyanidine solution. As the laccase, there maybe used the one that is secreted by Pycnoporus coccineus, a wood-rottingfungus, in a culture medium, and the method for producing it can beobtained by the method described in Japanese Patent Laid-OpenPublication 6-287516.

In addition, laccase may be the one which is obtained by the method withuse of a recombinant microorganism into which a laccase gene ofBacidiomycetes has been introduced by gene manipulation.

Furthermore, as the laccase may be used the one marketed for examplefrom Funakoshi K.K., which is available if desired.

The amount of laccase added to the proanthocyanidine solution variesalso depending on the concentrations of proanthocyanidine, and forexample an enzyme solution having an enzyme activity of 250 U/ml may beadded in an amount of 0.01-1% to the solution having theproanthocyanidine concentration of 0.2%.

Also, the proanthocyanidine solution can be turned into various colorsby the co-existence of metal ions. For instance, the gray coating can beformed by the co-existence of an iron ion.

The coating material according to the present invention has thefollowing effects:

(1) the coating having a natural grain of wood may be formed;

(2) a uniform coating may be formed;

(3) a material to be coated has an improved durability and hardlysoiled;

(4) the coating will hardly fade;

(5) the coating absorbs ultraviolet rays to protect the grain of wood;

(6) a coating material having a constant composition of components maybe supplied stably;

(7) the coating is odorless, and generates no harmful smoke upon burningof it, which is thus not deleterious;

(8) the coating contains no deleterious materials;

(9) the coating can be anticipated with having anti-bacterial effect;and

(10) the coating can be anticipated with having deodorant effect.

Examples are illustrated below.

EXAMPLE 1

Commercially available proanthocyanidine extracted from grape seeds("KPA-40"; manufactured and marketed from Kikkoman Corp.) was dissolvedin tap water to a concentration of 0.2% (A), 1% (B) and 5% (C) andcoated on Japanese cypress boards with a brush.

Coating was repeated three times with every 10 minutes, then leftstanding by the window, and the coating condition was observed by thenaked eye on 30 days after coating. The results are shown in Table 1.

                  TABLE 1                                                         ______________________________________                                                  Immediately 30 days after                                                                  after coating coating                                  ______________________________________                                        A (0.2%)    Transparent,  Colored slightly                                       incapable of yellowish brown                                                  distinguishing                                                                whether it is                                                                 coated or not                                                                B (1%) Slightly Colored pale                                                   yellowish brown yellowish brown                                              C (5%) Pale yellowish Colored brown                                            brown                                                                      ______________________________________                                    

EXAMPLE 2

Commercially available laccase (enzyme activity: 250 U/ml; FunakoshiK.K.) was added in an amount of 0.1% to the same proanthocyanidinesolution as used in Example 1. The resulting solution was coated in thesame manner as in Example 1, the coated material were left standing, andthe coating condition were observed on 7 days after coating. The resultsare shown in Table 2.

                  TABLE 2                                                         ______________________________________                                                Immediately after                                                                            7 days after                                             coating coating                                                             ______________________________________                                        A         Transparent, incapable                                                                         Colored pale                                          of distinguishing yellowish brown                                             whether it is coated                                                          or not                                                                       B Slightly yellowish Colored slightly                                          brown brown                                                                  C Pale yellowish brown Colored brown                                        ______________________________________                                    

EXAMPLE 3

KPA-40 (manufactured by Kikkoman Corp.) was dissolved in hot water at70° C. so as the concentration to be 20% (w/v) and 30% (w/v) and coatedtwice on pine tree boards, respectively. After first coating, theseboards were subjected to natural drying for 30 minutes, then to secondcoating, and the excess of coating material was immediately wiped offwith cloth to finish coating. The boards were left standing as such, andthe coating states were observed. The results are listed in Table 3.

                  TABLE 3                                                         ______________________________________                                                   Immediately 30 days after                                            after coating coating                                                       ______________________________________                                        A (20%)      Deep yellowish                                                                              Pale reddish                                          brown brown                                                                  B (30%) Pale reddish Reddish brown                                             brown                                                                      ______________________________________                                    

What is claimed is:
 1. A process for treating wood, paper or fiber whichcomprises applying thereon, an aqueous composition containing an amountof 0.1 to 50% by weight of proanthocyanidine.
 2. A process for treatingwood, paper or fiber which comprises applying a composition thereon,said composition comprising proanthocyanidine, and oxidase or peroxidasewhich may act on said proanthocyanidine as a substrate.
 3. A process fortreating wood, paper or fiber which comprises applying a compositionthereon, said composition comprising proanthocyanidine and laccase.
 4. Aprocess for treating wood, paper or fiber which comprises applying acomposition thereon, said composition comprising proanthocyanidine, andoxidase or peroxidase which may act on said proanthocyanidine as asubstrate, said proanthocyanidine dissolved at a concentration of0.1-10% by weight in water or in an aqueous solution of alcohol atambient temperature.
 5. A process for treating wood, paper or fiberwhich comprises applying a composition thereon, said compositioncomprising proanthocyanidine, and oxidase or peroxidase which may act onsaid proanthocyanidine as a substrate, said proanthocyanidine dissolvedat a concentration of 10-50% by weight in water or in an aqueoussolution of an alcohol at a temperature of 35-70° C.